Projection photolithography has been
used as a fabrication method for radial
grove gratings. Use of photolithographic
method for diffraction grating fabrication
represents the most significant
breakthrough in grating technology in
the last 60 years, since the introduction
of holographic written gratings. Unlike
traditional methods utilized for grating
fabrication, this method has the advantage
of producing complex diffractive
groove contours that can be designed at
pixel-by-pixel level, with pixel size currently
at the level of 45×45 nm. Typical
placement accuracy of the grating pixels
is 10 nm over 30 nm. It is far superior to
holographic, mechanically ruled or
direct e-beam written gratings and
results in high spatial coherence and low
spectral cross-talk. Due to the smooth
surface produced by reactive ion etch,
such gratings have a low level of randomly
scattered light. Also, due to high
fidelity and good surface roughness, this
method is ideally suited for fabrication
of radial groove gratings.

These would serve as
roughing pumps for vacuum
systems of miniature
instruments.
Miniature scroll pumps have been
proposed as roughing pumps (low-vacuum pumps) for miniature scientific
instruments (e.g., portable mass spectrometers
and gas analyzers) that
depend on vacuum. The larger scroll
pumps used as roughing pumps in some
older vacuum systems are fabricated by
conventional machining. Typically, such
an older scroll pump includes (1) an
electric motor with an eccentric shaft to
generate orbital motion of a scroll and
(2) conventional bearings to restrict the
orbital motion to a circle.

Pliable, unfired preforms deploy in-situ to save fuel and weight costs.
In this innovation, light weight, high
temperature, compact aerospace structures
with increased design options are
made possible by using self-assembling,
flexible, pre-ceramic composite materials.
These materials are comprised of
either ceramic or carbon fiber performs,
which are infiltrated with polymer precursors
that convert to ceramics upon
thermal exposure. The preform architecture
can vary from chopped fibers
formed into blankets or felt, to continuous
fibers formed into a variety of 2D or
3D weaves or braids. The matrix material
can also vary considerably. For demonstration
purposes, a 2D carbon weave
was infiltrated with a SiC polymer precursor.
The green or unfired material is
fabricated into its final shape while it is
still pliable. It is then folded or rolled
into a much more compact shape, which
will occupy a smaller space. With this
approach, the part remains as one continuous
piece, rather than being fabricated
as multiple sections, which would
require numerous seals for eventual
component use. The infiltrated preform
can then be deployed in-situ. The component
can be assembled into its final
shape by taking advantage of the elasticity
of the material, which permits the
structure to unfold and spring into its
final form under its own stored energy.
The pre-ceramic composites are converted
to ceramics and rigidized immediately
after deployment.

Alternative computational strategies
for the Discrete Fourier Transform
(DFT) have been developed using analysis
of geometric manifolds. This
approach provides a general framework
for performing DFT calculations, and
suggests a more efficient implementation
of the DFT for applications using iterative
transform methods, particularly phase
retrieval. The DFT can thus be implemented
using fewer operations when
compared to the usual DFT counterpart.
The software decreases the run time of
the DFT in certain applications such as
phase retrieval that iteratively call the
DFT function. The algorithm exploits a
special computational approach based
on analysis of the DFT as a transformation
in a complex vector space. As such,
this approach has the potential to realize
a DFT computation that approaches N
operations versus Nlog(N) operations for
the equivalent Fast Fourier Transform
(FFT) calculation.

Designs of gores reflect multiple considerations of assembly, stowage, and deployment.
An improved method of designing
complexly shaped inflatable shells to be
assembled from gores was conceived for
original application to the inflatable outer
shell of a developmental habitable spacecraft
module having a cylindrical midlength
section with toroidal end caps.

A film-growth process was developed
for polycrystalline mercuric iodide that
creates cost-effective, large-area detectors
for high- energy charged-particle
detection. A material, called a barrier
film, is introduced onto the substrate
before the normal mercuric iodide film
growth process. The barrier film
improves the quality of the normal film
grown and enhances the adhesion
between the film and the substrate.

Successful artificial photosynthesis is significant for future human/robotic exploration and
terrestrial carbon emissions control.
A new cell designed to mimic the photosynthetic processes
of plants to convert carbon dioxide into carbonaceous products
and oxygen at high efficiency, has an improved configuration
using a polymer membrane electrolyte and an alkaline
medium. This increases efficiency of the artificial photosynthetic
process, achieves high conversion rates, permits the use
of inexpensive catalysts, and widens the range of products generated
by this type of process.

Question of the Week

This week's Question: A recent study created by the Arizona-based Paragon Space Development Corporation says its life support system could help humans survive on Mars. The proposed Environmental Control and Life Support System, the company says,...